Bupropion
Bupropion is a noradrenaline-dopamine reuptake inhibitor,See this for explanatory notes on what this means antagonist'That is, it blocks the receptors that mediate the pleasurable effects of nicotine and 'atypical antidepressant.Brayfield, A, ed. (22 October 2013). "Bupropion". Martindale: The Complete Drug Reference. London, UK: Pharmaceutical Press. Retrieved 28 July 2014. It is primarily used to treat nicotine dependenceThat is, to help people quit smoking under the brand names Prexaton, Zyban, although in some countriesFor example the , Canada, Hong Kong and Singapore it is also sold under the brand name, Wellbutrin, for the treatment of depression.Saiz Ruiz, J; Gibert, J; Gutiérrez Fraile, M; Bobes, J; Vallejo, J; Iglesias, C; Iriarte, V (2011). "Bupropion: efficacy and safety in the treatment of depression." (PDF). Actas Espanolas de Psiquiatria. 39 Suppl 1: 1–25. PMID 22983817. It can also be used in the treatment of another mood disorder called seasonal affective disorder. Side effects Its major dose-limiting side effect'''This means this side effect is more frequent at higher doses than at lower doses. In fact it was initially withdrawn from the U.S. market soon after it was introduced around 1985 due to this side effect. It was later re-introduced with restrictions on its maximum dosage to be used clinically. is '''seizures (although usually they are mild and not life-threatening) and consequently can be quite toxic in overdoses 'when compared to other antidepressants.Hawton, K; Bergen, H; Simkin, S; Cooper, J; Waters, K; Gunnell, D; Kapur, N (May 2010). "Toxicity of antidepressants: rates of suicide relative to prescribing and non-fatal overdose.". ''The British Journal of Psychiatry '''196 (5): 354–8. doi:10.1192/bjp.bp.109.070219. PMC 2862059. PMID 20435959. Despite this seizures are still uncommon with its use, except in overdose, of course, occurring in around 0.4% of patients treated with 450 mg/day or less of the drug. Two other rare, yet potentially fatal, side effects of bupropion are allergic reactions like anaphylaxis 'and 'angioedema. Other serious, yet uncommon/rare side effects include mania, suicidal thoughts or behaviour (that is, attempting/committing suicide), liver damage (even to the point of failure requiring a transplant), psychosis, aggression and Stevens-Johnson syndrome. Compared to other antidepressants it is associated with a lower risk of weight gain, mania,A dangerously high mood, usually associated with bipolar disorder. drowsiness and sexual dysfunction.As you can probably guess this is an umbrella term referring to impotence, that is, difficulty achieving an erection in guys, difficulty achieving an orgasm, reduced libido, etc. Compared to other second-generation (newer) antidepressants it is associated with a''' relatively low rate of discontinuation''' (that is, people stopping the drug), although its efficacy (that is, its effectiveness) is unremarkable; it is worth noting, however, that the differences in effectiveness vary little from antidepressant to antidepressant, hence for patients this is probably meaningless. Its common side effects (occurring in over 1% of those treated with it) include: * Dry mouth * Nausea * Vomiting * Constipation * Weight loss * Hives * Fever * Insomnia (reduced sleep/difficulty falling asleep) * Nightmares * Anxiety * Concentration difficulties * Dizziness * Agitation * Itching Overdoses Overdoses cause symptoms such as: hallucinations, nausea and vomiting, high heart rate, seizures (which occur in about a third of all overdose cases), coma and death.Taylor, D; Paton, C; Shitij, K (2012). Maudsley Prescribing Guidelines in Psychiatry (11th ed.). West Sussex: Wiley-Blackwell. ISBN 978-0-47-097948-8. Treatment usually consists of limiting absorption'''Via activated charcoal and stomach pumps if possible (like if the affected person gets medical attention within one hour of overdose). Beyond this treatment is supportive (that is managing symptoms/complications as they arise), for example benzodiazepines (like diazepam Valium) may be used to control seizures. '''Dialysis and diuresis (that is, putting one on a saline water drip so as to force the body to urinate it out faster) are likely useless, due to the low water solubility of bupropion and the high protein binding of it and its active metabolites. Interactions Bupropion inhibits '''the liver enzyme CYP2D6''' (which is required for the metabolism of numerous drugs, including codeine, fluoxetine Prozac and tamoxifen) very potently, and depends on CYP2B6 for metabolism. CYP2B6 is induced (potentially reducing the effectiveness of bupropion) by certain antimicrobials (like efavirenz, rifampicin and ritonavir) and certain anti-seizure medicines (like phenobarbital and phenytoin). It is also inhibited (increasing the potential for seizures and other side effects) by certain blood thinners like clopidogrel and prasugrel. Properties Structurally bupropion is chemically related to the amfetamines, although it possesses minimal potential for abuse or producing euphoria (that is, a high). Two salt forms are available for clinical use: the hydrobromide (HBr) and hydrochloride (HCl) salts. Although, HCl salts are the only ones available in Australia. Bupropion has a half-life of 14 hours, hence necessitating three times daily dosing for immediate-release '''(IR) formulations''' (this means it releases the drug as rapidly as it can into the digestive tract upon ingestion). Sustained-release '''(SR) formulations''' (which release the drug relatively slowly) are the only formulations available in Australia and the U.K.; they have a half-life of 20 hours (brand names: Clorprax, Prexaton, Zyban); and need to be dosed twice daily. Extended release '''(XR) formulations''' (which release the drug even more gradually, facilitating once daily dosing) can be taken once daily and are usually called by the brand name Wellbutrin XL but are only available in countries where bupropion is marketed to treat depression. It is about 84% plasma protein bound and is principally metabolized by CYP2B6 to the following active metabolites: hydroxybupropion '(in ''animal studies it was purported to be half as active as bupropion), '''threohydrobupropion (one-fifth as active in animal studies) and erythrohydrobupropion (also one-fifth as active in animal studies). Structures External links * DailyMed Wellbutrin XL package insert (written for healthcare professionals) * Martindale: The Complete Drug Reference (JCU login required) * Wikipedia entry (featured article). * TGA eBusiness Services (view this link if you do not know this acronyms): Clorprax (CMI, PI), Prexaton (CMI, PI), Zyban (CMI, PI). Notes Reference list Category:Antidepressants Category:Atypical antidepressants Category:Depression Category:Seasonal affective disorder Category:Smoking cessation